The Murderer of Danville
by bilaterus
Summary: Strange deaths have been happening in Danville and Isabella thinks she knows who's behind them. Suddenly, she finds herself in a house of horrors, trapped by the murderer. Will she make it out alive? Viewer discretion advised.
1. Chapter 1

**As part of my bid to write as much variety as possible, I bring you a horror story that Galaxina and I discussed briefly aages ago. I hope it chills you to the core.**

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"Ferb is a hit man!"

Phineas's usual cheeriness turned into confusion. "What?"

"Ferb!" Isabella repeated urgently. "He's a hit man!"

It was not how Isabella usually entered the backyard. Phineas took a moment, studying Isabella's expression, and saw she was genuinely panicked. And she was. Isabella wasn't one to jump to conclusions, especially with an accusation as serious as murder, but the thought had occurred to her in a flash that very morning, and as much as she turned over the facts in her mind, they only confirmed it.

Phineas, however, was not so easily convinced.

"Isabella, I never thought I'd say this, but you've gone totally crazy."

"Hear me out," Isabella said, looking around nervously to make sure Ferb was not in the vicinity. She then produced the _Daily Danville_ and pointed at the front page headline: 'French Ambassador Killed: Situation Described as Fishy'.

"He and Mayor Doofenshmirtz were visiting the Danville Aquarium when the glass to the shark tank broke and he was ripped to pieces by a great white!"

A shadow fell across Phineas's face. He studied the newspaper article intently for a moment. "Well... despite the delightful nautical play on words in the headline, the article suggests it was just an accident," Phineas said seriously.

"Maybe so," Isabella admitted. "But take a look at yesterday's paper!" She swapped that day's _Daily Danville_ she was holding with the previous day's. "Look! 'Visiting British Dignitary Hit By Freak Lightning Strike… 27 Times'! And the day before that, 'Chocolate Factory Tour Turned Sour When German Ambassador Is Killed By Exploding Chocolate Bar'!"

"But Isabella, those were all described as accidents," Phineas said. "Albeit highly unfortunate ones for the people involved. And even if they weren't, there's no evidence Ferb was behind any of it!"

"C'mon, Phineas. Who else would kill people like this? It's totally Ferb's style!"

"Nah, Ferb wouldn't hurt a fly," Phineas said. "Oh, unless it was some sort of evil bionic fly…"

"And you two have been doing more secret solo projects these days," Isabella continued, undeterred. "And I'll bet his 'projects' have been assassinations! We need to get to the bottom of this!"

It really was a horrible accusation to make, and Isabella desperately wished it wasn't true. But it all lined up. What was that quote? _When you have eliminated the impossible, whatever remains, however improbable, must be the truth._ And it seemed to Isabella that there was only one improbable truth left. Ferb did seem to fit the bill, too, what with his shifty eyes and silent, secretive demeanour. It's always the quiet ones.

And if it was true, then that put her and Phineas in more danger with each passing second.

The red-headed inventor was silent, deep in thought for what felt to Isabella like an eternity. Then, finally, he nodded, in what seemed like acceptance. "Ok. Have you told anyone else about this yet?"

Isabella relaxed slightly, now that Phineas was on board. "No, just you." Ferb was his brother, so Isabella had decided that he deserved to hear her suspicions first. And if anyone could help her, it was Phineas.

"I see. Well, I need to see a man about some parts for one of those solo projects of mine," Phineas said, his expression brightening again as he made to leave the backyard. "But right after I get back, we'll get the gang together, perhaps sans Ferb, strange as it'll be, and get to the bottom of this."

"Oh, er, ok…" Isabella said. She then realised that Phineas was leaving her alone, possibly a stone's throw away from Ferb. "Oh, Phineas, er, mind if I come with you?"

"No!" he said, a little suddenly. "I mean, it is a surprise for you, after all. And don't worry, even if Ferb was secretly evil, he wouldn't get you out in broad daylight in our backyard. That'd be way too boring!"

"I guess... where is he, anyway?"

"He's just inside. Relax, Isabella, Ferb's not a psychopathic murderer. Trust me," Phineas winked.

Isabella may have been more reassured by this had she not felt the gaze of a shadow from a bedroom window.

"Stay right here," Phineas instructed, and he then rushed out of the backyard, unusually quickly.

Realising her heart was racing and that there was nothing to worry about, Isabella slumped against the tree. Phineas was right: Ferb wouldn't get her here and now. Besides, she was a Fireside Troop leader. When she had her guard up, she could defend against anything. Phineas would get back and everyone would come together and they'd all get to the bottom of this.

And then Phineas would present his secret project, the one just for her! She squealed inwardly. What could it be? She allowed her mind to wander in the field of possible inventions and timelines. Would it be a romantic journey above the clouds? Maybe he'd carved her likeness out of marble? A giant bouquet of flowers? Or perhaps he was simply going to take her hand in his, stare lovingly at her with those great big eyes of his, click his fingers and whisk them away to have the Paris love scene that she had wanted for so long...

Isabella stirred with a groan, her eyes still closed. Her head throbbed painfully. The ground felt hard to the touch and the air smelled musty and damp, in stark contrast to the soft grass and fresh air of the backyard.

Strange, since Isabella didn't remember falling asleep at all, let alone in a place like this.

She concentrated on any memories that might explain how she got here, only her mind was blank past Phineas leaving her in the backyard. But her throbbing head suggested that despite Phineas's reasoning, Ferb must have done something after all, knocking her out and leaving her here.

But where was 'here'? She could hear the humming of some technology, adding evidence that Ferb had a hand in where she had ended up. She'd have to keep an eye out for him. Slowly, unaware and afraid of what she would see, her eyes opened... to meet an unexpected pure darkness.

It was at this moment she was tempted to scream and call out for help. But then she remembered she was Isabella Garcia-Shapiro, leader of Fireside Troop 46321, and now was not the time to panic. Instead, the Fireside Guide to Handling an Unfamiliar Situation appeared in her mind. Step 1 was to keep composed. She should not panic. Step 2 was to assess the situation properly.

Isabella realised she was curled up on the ground and carefully made to stand up. She could see a little into the darkness now, her eyes having adjusted. There seemed to be pickle jars filled with liquid of some sort on various pedestals around the room, translucent and eerie tubes connecting to and from them. She stared in bewilderment, turning to take in the rest of the room.

Then, suddenly, the lights flashed on, and she came face to face with a single human eye, looking right at her.

The grisly body part was floating in the jar, suspended in the unidentified liquid. Isabella gasped and staggered backwards. She crashed into another pedestal. A loud beep sounded and Isabella felt a liquid trickling down her back. The smell of iron filled her nose and she spun around sharply, fearing the worst of the fluid. Blood. It covered her back and shoes and was still spilling out from the tap she had triggered.

_What is this?!_

Desperately, she tried to escape the spreading pool of crimson on the floor. Backing away from it past the various pedestals, she could now see their macabre contents. A severed human hand. A person's nose. A foot. Hearts and livers, stomachs and intestines, all stored in jars like some mad scientist's trophy room.

Isabella felt sick to her stomach. She wished desperately for this all to be a dream, but the sticky blood on her clothes and hands and the ache in her back confirmed that this was all too real.

_This must be one of Ferb's secret places,_ Isabella realised with a start. But she then heard a voice that was to change everything.

"Hey, Isabella!"

"Phineas," she exclaimed in relief, and instinctively moved towards the sound of the voice.

"I take it the anaesthetic has worn off?"

Isabella realised the voice was coming from a speaker, and, looking up, spotted it in the corner of the room. But a small microphone seemed to be below it and, judging from his response time and questioning, he could hear her too.

"Phineas, thank goodness you're here! Ferb dumped me into this horrible room filled with-"

"Woah there Isabella. I don't mean to cut you off, but if you tell me where you are, it'll spoil all the fun!"

"Wait, what?" Isabella asked, bewildered.

"And I already told you, Ferb's not responsible for any of this. He's just too nice!"

"But who else could it be?" she said exasperatedly. "All the murders were creative and meticulous, and Ferb is the most creative and meticulous person there is! Well, except..."

Isabella froze. Except the one other person who was at least as creative and meticulous as Ferb Fletcher.

"Yup, it's me!"

Isabella turned slowly, in utter disbelief, towards the speaker. Phineas's voice hadn't changed in tone at all, but suddenly it sent icy cold shivers down Isabella's spine.

_It couldn't be Phineas. It just couldn't be!_

"Haha, Isabella, you sound like Ferb right now! In that you're not saying anything but I know exactly what you're thinking. But I'm afraid it's true. "

There it was again: that casual, easygoing voice that had gone from warm and inviting to chillingly disturbing in a single moment. A million questions flooded Isabella's mind, but she couldn't articulate any of them.

"I had better explain what's going on. You see, someone hired me online to destroy Mayor Doofenshmirtz's career without being detected. I thought it was a great opportunity. I mean, just think of all the creative possibilities there are of diminishing someone's reputation!"

"So you settled on assassinating visiting dignitaries?" Isabella asked, already knowing the terrible answer.

"Yup! Without being detected, of course. But that's just part of the challenge!"

"Does… does Ferb know about this?"

"Well, he knows I'm doing something. And I know he's doing something too, but it's a secret. I'd tell you, but then I'd have to kill you… hehehe, 'kill you'. I mean, I have to anyway, but I'd better not tell you what Ferb's secret is. A promise is a promise, after all."

Isabella could almost imagine him wiping a tear from his eye as he chuckled at the joke he'd just thought of. She felt like laughing too, like a madwoman, at the sheer skew of Phineas's morals, that he was above breaking a promise to his other childhood friend just as he was about to kill her. The entire thing was utterly crazy.

Screw the Fireside Manual. Now was the time to panic.

"I mean, it's nothing personal, Isabella, but I can't have people knowing about what I do. That'd compromise the entire mission. But don't worry, I came up with a way that makes it fun!"

"Phineas, I can't think of a single way that killing me could possibly be fun!" Isabella shrieked, in desperate hysterics. "I never thought I'd say this, but you've gone totally crazy!"

"Hear me out. See, we're currently in a building of my design. It's made out of rooms that are like blocks that can rearrange themselves and connect to each other in different ways. I had the building drop us both into random rooms, and my job is to find and disintegrate you with my particle blaster as soon as possible while you try to hide and the building shuffles us around! Pretty cool, huh?"

_No, no it isn't!_

Isabella wanted to break down and cry. How, how could she live side by side with someone for so long, knew inside out, and have such a crush on no less, and not realise he was capable of all this unspeakable madness?

And he was going to do more. Isabella had no doubt in her mind that Phineas would blast her when he got the chance. He was a monster, a smiling psychopath. She still didn't fully believe it, it seemed horribly wrong, but even as she thought of those words they made a twisted kind of sense at the same time, these words that went completely at odds and also perfectly aligned with the profile of her smiling neighbour, who lived to be creative and seize the day. Whose motto in life was the belief that you can achieve anything if you put your mind to it.

Even murder.

She couldn't let him get away with it. She wouldn't let him get away with it. For the second time, she reminded herself that she was Isabella Garcia-Shapiro, and she was a fearless Fireside troop leader. Well, she was supposed to be fearless. Isabella became acutely aware of how much her knees were shaking.

No, she could do it. Right now, escaping was her top priority.

With that in mind, she began towards one of the room's doors, gingerly avoiding as much of the blood on the ground as she could. It was possible that she was moving closer to Phineas, but standing around wouldn't help her find the exit. And she didn't like the idea of doing nothing while Phineas closed in on her. She laid a hand on the doorknob, but a small shuffling noise on the other side of the door made the hairs on the back of her neck stand on end.

_What was that? Is it Phineas? _She listened hard, pressing her ear against the door. Nothing. _Did I imagine it?_ If she did, then shed be one step closer to the exit, but if it was Phineas...

The danger paralysed her. The doorknob was loose to turn but now it might as well have been superglued in place as far as Isabella was concerned. There was no way she could turn it knowing Phineas may be on the other side.

"Wow, three rooms already and I've still not found you! Isn't this exciting?"

If Phineas really was in the other room, then surely she'd have heard his voice through the door, but Isabella only heard it through the speaker. Or perhaps the walls were better soundproofed than their appearance suggested? Either way, Phineas's words were a sharp reminder to Isabella that she was getting nowhere fast. Mustering all her courage, Isabella took a deep breath and, with one motion, turned the doorknob and pushed the door open.

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**See you at the same time next week.**


	2. Chapter 2

**Well, after such a great response to the first chapter, I simply had to update three days in advance. I hope it's... well, enjoyable and not enjoyable at the same time.**

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Isabella braced herself for the worst as the door swung open. But apart from a foul, yet strangely familiar, odor, nothing hit her. And the room was pitch black. Her body relaxed slightly but Isabella tried to resist its instinctive reaction. She had to remain logical in this place, or she'd never make it out alive. Isabella reminded her body that the darkness could still be hiding anything. Then she had a brainwave.

_The lighting is motion-sensitive!_ It explained why it had suddenly come on without warning earlier, and why she hadn't seen any obvious light switches. Again, her body wanted to be reassured by this, as it meant that there was nothing in the room which was moving. Which meant no Phineas.

But as the room she was currently standing in had showed her, there could be any number of unspeakable unmoving horrors just waiting in the darkness.

And it was also possible there was something in there, but it was not moving very quickly. Something had made the sound she had heard, after all. Isabella just hoped that it was a machine of some kind.

But there was only one way to find out for sure. Tentatively, Isabella reached a hand in, and waved it vigorously.

The light slowly flickered on. Isabella could make out the features of a large bookcase, with books scattered all across the floor. The intensity of the light reached its peak and there was a loud groan from the left hand corner of the room. Isabella spun around sharply. What she saw made her leap out of her skin.

Or rather, _who_ she saw.

It was Buford. But not the usual pale-skinned bully she knew. This Buford wore his distinctive black skull shirt, but it was torn and dirty, and revealed molding, fungal arms. His face was horribly disfigured and long lines of stitches held together patches of his skin, in a Frankensteinian style. He was recoiling from the bright light, and began staggering towards her with surprising speed, dragging a partly broken leg with him.

Isabella leapt back into the Jar Room and slammed the door shut. But it didn't close. She looked down to see Buford's stubby arm poking through the gap, his hand grasping at the air. Isabella felt his finger brush against her and she recoiled, slamming the door with even more force. Buford groaned in pain. But the door still wouldn't shut.

Then, suddenly, the entire room shook under Isabella's feet. There was a huge mechanical lurching sound, and she felt everything accelerating to the left. She pushed her back against the door, digging in her feet, to prevent the force flinging her across the room. Then, as suddenly as the shaking began, it ended, with a large ding, as if she was in a mall elevator that had just reached the correct floor.

Isabella placed a hand on her chest, her heart beating at least a hundred times a second and breathing at least as fast. She had to get her bearings again. As her mental state returned to normal, she realised that the door she was leaning against had shut fully. Buford must have been pulled away by the room shift.

She sunk to her knees. That incident had exhausted her mentally and was taking its toll physically. The difficulty it indicated in even moving through one room now loomed over her: if every room was going to be as traumatic as these two, then she was doomed to stay in this room for the rest of her life. Which would be until Phineas found her.

Well, she had lasted longer than Buford had. A horrible image arose in Isabella's mind, one of Phineas poring over Buford's corpse laid out on a mad scientist's operating table, like something out of a bad horror film, as the crazed red-headed inventor looked over his specimen with the same curiosity and fascination with which he regarded as a new puzzle game. In her mind, Phineas then took a knife and, with all the precision of a master surgeon, sliced the skin apart to get a hold of the grisly insides, biting his lip in concentration, or perhaps with his tongue slightly out and an eye closed as he focused in his unique, irresistible style...

Isabella wanted to cry. She hated that she couldn't stay logical. She hated that she could do nothing but sit, paralysed, wanting to cry out of despair and lost love.

But no, this Phineas was not the one with which she fell in love. This Phineas was a monster. Still, would her body fight Phineas, or rush into his arms and plead for the life they could have together?

Her question was answered immediately. She heard a creaking from the other side of the room and immediately recognised it as a door swinging open. Her body instinctively made for cover without a sound, positioning herself behind one of the stands supporting the jars. It was a good position, one that if Phineas walked right through to the door she was just at, he would not see her.

Isabella realised with a start that there was no chance of Phineas doing that. The lights were on. That indicated to Phineas that she was in there, if they really were motion-sensitive. Even if they stayed on for a long time after detecting any motion, Phineas would deduce that she might be in that room, and look around thoroughly, surely finding her if he did so.

It wasn't reassuring, and Isabella could already hear slow, measured footsteps entering the room. But then she looked down and saw something that really made her heart sink.

Footprints. A trail of red footprints leading right to the spot she was crouching in now. They were hers, of course. Footprints left by her as she panicked, oblivious to the crimson blood clinging to her shoes and leaving traces of her path.

So this was how it ended. Killed, while cowering in fear, by her best friend and crush. No future with Phineas like she always dreamed. So much for the words she had held onto since early in the summer: "Aunt Isabella! That means I'm going to marry Phineas!". Then for some reason, the joking "or Ferb" addition swam into mind and all her previous dreams of her future with Phineas appeared in a flash, but with a handsome, green-haired Englishman in Phineas's place instead.

The footsteps began inching closer, after having paused momentarily about a meter away. So Phineas had seen her footprints and was coming for her. She had resolved to go with a fight, where there was a slim chance she could knock Phineas's weapon out of his hands and overpower him. But she couldn't stop shivering at the thought of the much more likely outcome.

The footsteps reached her.

With all the adrenaline she could muster, she leapt at her attacker, knocking him to the ground, throwing punches and kicks blindly, one of which connected clean on his cheek. He recoiled, and she raised a fist to hit him squarely in his large flat nose.

_Flat nose… Ferb?!_

She looked down at him in disbelief. She was indeed standing over Ferb, who had raised his arms protectively. She was breathing heavily again, and Ferb was looking at her with terror in his eyes. Well, no wonder. She imagined the scene from Ferb's point of view: that in a flash, his crazed, blood-covered friend began relentlessly attacking him. Isabella backed down, and Ferb slowly rose to his feet, still a little wary of her. He was clutching a gun of some sort.

"Ferb," Isabella began. "What are you doing-" but Ferb signalled her to be quiet and pointed at the microphone in the corner of the room.

Ferb slowly got over the shock, and his expression changed to one of sadness and pity. He had come to rescue her, Isabella realised. She had accused him of murder, and now had viciously attacked him, but he was still going to go against his step-brother, his other half, to save her. Because he was Ferb. Tears welled up in her eyes as her body accepted the ordeal was over, and she finally succumbed to it, sinking to her knees as Ferb rushed to comfort her in a warm embrace.

It was over. It was finally over.

But through her vision blurred by tears, a figure appeared in the doorway of the other side of the room. Ferb too spun around, to see his step-brother in the doorway.

Phineas grinned. "Found ya!"

Time seemed to slow to a crawl. Ferb and Phineas both raised their strange weapons, firing almost identical energy blasts within milliseconds of each other. The blasts collided in a small explosion, seemingly restoring time again, and all three of the now-combatants moved swiftly to cover behind nearby pillars. Phineas and Ferb were shooting at each other now, jars shattering and spewing their horrific contents of body parts and liquid everywhere.

"Good to see ya, Ferb! It would've been boring if you hadn't turned up!"

Isabella was suddenly filled with rage. How could Phineas still not understand the gravity of the situation, and talk about it like they were visiting the grocery store? Did he just care about excitement, no matter what sick source it came from? She would never forgive him now, even if he confessed his undying love and begged for the rest of his life. She would put an end to this.

Isabella didn't have a weapon, but a human heart slid out nearby from a shattered jar, and she grabbed the potential projectile immediately, ignoring its slimy texture.

_Pitching patch, don't fail me now_, she prayed. as she aimed it at directly at Phineas.

It connected. For a second, Phineas turned, distracted, and Ferb seized the opportunity to fire a final shot with pinpoint accuracy at his step-brother's chest. Surprise flashed momentarily on Phineas's face, then he slumped to the floor, finally still.

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It was a long time before Isabella returned to her usual bright, cheery self. It's difficult to trust people after learning that the most cheery and positive person you know was hiding pitch black secrets on the inside. She'd have gone down the path of Isabella-2 - icy cold - were it not for Ferb, the only person she knew right down to the core.

Ferb too was having a difficult time. After the incident, some men in uniform came to take the knocked out Phineas away, giving the rest of the Flynn-Fletchers the excuse that the government needed Phineas Flynn for a classified mission. So at least Ferb didn't have to live with the fact that he had killed his other half, he just had to live with both the truth and the lie. But it raised a potential problem: where do you lock up someone that resourceful? Having to design and maintain the maximum-security prison to hold Phineas took a heavy toll on the usually stoic Ferb. He was just a kid, after all. He became increasingly solitary, eventually seeing only Isabella, the only other person who knew the truth.

Zombie Buford returned to his family. His mother noticed immediately that both his diction and odor had markedly improved, but was angry at him for letting his clothes get ruined. Still, though, it meant the summer would never be the same again - inventing was now out of the question. Too many memories.

But eventually they had to. It was in Ferb's blood, and Isabella just couldn't do the moping girl thing forever. So Isabella resolved to replace her "Whatcha doin'?'" with "I know what we're doing today!" and the two called the rest of the gang to the backyard. Exchanging smiles with Ferb, her hands in his, Isabella welcomed the gang and explained the Big Idea for the day.

The first thing they built? A rollercoaster. The symbol for a new beginning.

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**I'm both sorry and not sorry to have put you through that.**

**Onto something more cheerful. I've added a section to my profile for you to check out: Practical Advice for Aspiring Writers! It's a section that I hope might be of some benefit to everyone. **

**Take care!**


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